1. Field of the Invention
The present invention relates to a method of recording and reproducing information, and more particularly, to a method of recording and reproducing information capable of realizing high-speed rewriting of data.
2. Description of the Related Art
Generally, in recording data into a memory card, efficient data manipulation is enabled by allocation of a physical recording area to logical space. Physical-to-logical mapping is performed by a method in which, as shown in FIG. 11, a logical address is assigned to each of physical constituent units (A, B, C, . . . ). When the memory card is used, all logical addresses therein are read first, followed by creation of a logical/physical address translation table which is used for translation from logical to physical addresses thereby to allocate the recording area in the physical space to the logical space, so that non-contiguously recorded data set is made contiguous in a virtual space.
In a memory card such as NAND memory, direct modification to a data area already containing information is prohibited. Therefore, partially modifying the data area requires the following steps as shown in FIG. 13:
{circle around (1)} Read a data area containing locations of modification from the memory card and store it into an internal memory of a device;
{circle around (2)} Erase the previous data area in the memory card in physical constituent units (erase units) and modify the data area in the internal memory; and
{circle around (3)} Write the data area modified in the internal memory into unused constituent units within the memory card.
There is recently an accelerating trend toward enlarging the erase unit with increasing memory card storage capacity. As shown in FIG. 14, even when two pieces of modification data in a file are the same in byte-size, reading/writing of data requires more time as the erase unit enlarges, with the trend moving toward larger internal memory capacity.
Particularly in an FAT (File Allocation Table) scheme which is one of ways to manage data, an area called FAT area is modified every time data is added or erased. Such repetitive small modifications disadvantageously increase erase units of memory and lengthen the processing time.
In order to achieve high-speed rewriting of the FAT area, the Japanese Patent Application Publication No. 6-187205 discloses a method in which the FAT and a root directory are read into a main memory from an EEPROM (Electrically Erasable and Programmable ROM) upon power-up, and subsequent processing is executed by accessing the FAT and root directory stored in the main memory, and furthermore these FAT and root directory in the main memory are written back into the EEPROM upon power-down.